Examples of power tools used in tightening bolts or screws or drilling holes include a hand-held type power tool that has a grip portion whose axis extends in an up-down direction 3nd a main body provided on the to, end of the grip portion, the main body having an axis intersecting the axis of the grip portion such that the power tool can have a generally T-shaped or L-shaped configuration as a whole. As one example of this kind of power tool, Japanese Patent Laid-open Publication No. S60-196904 (“prior art reference 1”) discloses a power tool having a trigger provided on the top of a grip portion for movement along the axial direction of a body and a built-in speed control switch for controlling the rotation speed of a motor depending on the pulling amount of the trigger.
In such a power tool as disclosed in the prior art reference 1, a user should adjust the pulling amount of the trigger with a finger so as to perform a variety of tasks. For instance, if the user wishes to decrease the rotation speed of the motor, it is very difficult to stably keep the pulling amount of the trigger at, e.g., an intermediate level during the course of conducting an intended task. That is, this poses a problem in that great difficulty is encountered in constantly maintaining the rotation speed of the motor at an intermediate speed while carrying out the intended task.
Apart from the above-mentioned power tool wherein the main body is provided on the top end of the grip portion with its axis intersecting the axis of the grip portion such that the power tool can have a generally T-shaped or L-shaped configuration as a whole, Japanese Patent Laid-open Publication No. H6-254779 (“prior art reference 2”) teaches a reciprocating saw that has a grasping portion, a trigger provided on the grasping portion to control the rotation speed of a motor in proportion to the pulling amount thereof and a stopper portion for retracting and protruding movement with respect to a moving zone of the trigger. In this reciprocating saw, the stopper portion can be protruded into the moving zone of the trigger through the manual actuation of an operating portion, thereby limiting the maximum rotating speed of the motor.
According to the power tool taught in the prior art reference 2, the operating portion for creating movement of the stopper portion is arranged on the top surface of the power tool independently of the grasping portion to thereby ensure that no finger reaches the operating portion when the grasping portion is gripped by a user. Providing the operating portion on the top surface of the power tool in this way, however, raises a possibility that the operating portion might be inadvertently actuated through the contact with a tool resting surface as the power tool is placed on the tool resting surface when not in use. This may sometimes change the maximum rotation speed of the motor without the user knowing of such change. Another problem is that the operating portion is vulnerable to damage when the power tool is mistakenly dropped and struck against a floor or the like.